Printed circuit board including electromagnetic bandgap structure

ABSTRACT

Embodiments of the present invention provide a printed circuit board, which includes an electromagnetic bandgap structure disposed around an antenna, so as to prevent noise from being transmitted to the antenna. The printed circuit board includes an antenna, a circuit chip, a plurality of metal layers and a plurality of dielectric layers, a pair of transmission lines for transmitting a signal to the antenna, and an electromagnetic bandgap structure disposed between the antenna and the circuit chip and for preventing an electromagnetic wave from being transmitted from the circuit chip to the antenna.

CROSS REFERENCE TO RELATED APPLICATION:

This application claims the benefit of and priority to U.S. patentapplication Ser. No. 12/650,482, entitled “Printed Circuit BoardIncluding Electromagnetic Bandgap Structure,” filed. Dec. 30, 2009,which claims the benefit of and priority under 35 U.S.C. §119 to KoreanPatent Application No. KR 10-2009-0056534, entitled, “Printed CircuitSubstrate Using the Electromagnetic :Bandgap,” filed on Jun. 24, 2009,and Korean Patent Application No. KR 2009-0105670, entitled, “PrintedCircuit Substrate Using the Electromagnetic Bandgap,” filed on Nov. 3,2009, which are all hereby incorporated by reference in their entiretyinto this application.

BACKGROUND:

1. Field of the Invention

The present invention relates to a quartz vibrator and a printed circuitboard (PCB), and more particularly, to a PCB which includes anelectromagnetic bandgap structure that is disposed around an antenna soas to prevent noise from being transmitted to the antenna.

2. Description of the Related Art

Recently, as a radio communication device is required to have a largenumber of different functions, the number of components mounted on thedevice has increased and the size and thickness of the device have beenremarkably reduced, and thus the density of a PCB which is an importantcomponent of the device is on a continuously increasing trend.

When the density of the PCB is increased in this way, the distancesseparating the mounted components become reduced, and accordingly,signal interference occurs therebetween. A signal generated from acomponent has an influence in the form of noise on another adjacentcomponent.

In particular, depending on an increase in the density of the PCB, achip component which has been mounted around the antenna may he locatednearby the antenna, so that a signal generated from the chip componentaffects the antenna, undesirably deteriorating performance of theantenna.

Generally, communication is achieved in such a manner that the antennareceives power from the feed line of a main PCB to thus radiate radiofrequency to the outside.

In the case where the antenna is a FIFA or loop type antenna, theantenna simultaneously uses the ground and feed terminals of the mainPCB. In this way, when the antenna simultaneously uses the ground andfeed terminals of the main PCB, noise generated from the RF circuit ordigital circuit of the main PCB propagates to the inside or outside ofthe PCB and thus affects a radio frequency output, consequentlydeteriorating performance of the antenna in the frequency band affectedby noise,

Because noise has a direct or indirect influence on antenna performancealong the feed or ground line of the antenna, even when the antenna isdifferently designed, there is a limitation on an improvement in itsperformance.

Although such noise may be blocked using a passive element or an L/Cfiler, in the case where the propagation pathway of noise cannot beexactly determined, design lead time may be increased, undesirablyresulting in high cost.

Specifically, in the case where the propagation pathway of noise isunclear, many designs for blocking noise should be reexamined, and thusthe lead time is increased, undesirably causing a problem of increasingthe cost.

Furthermore, when the pathway of noise varies depending on changes inantenna design or a new noise source may be created, antenna performancemay deteriorate as a result.

SUMMARY:

Embodiments of the present invention have been made keeping in mind theproblems encountered in the related art and the present inventionintends to provide a PCB including an electromagnetic bandgap structurein order to prevent performance of an antenna from being deteriorateddue to noise inside the PCB,

According to an embodiment of the present invention, there is provided aPCB including an antenna, a circuit chip, a plurality of metal layersand a plurality of dielectric layers, a pair of transmission lines fortransmitting a signal to the antenna, and an electromagnetic bandgapstructure disposed between the antenna and the circuit chip in the PCBand for preventing an electromagnetic wave from being transmitted fromthe circuit chip to the antenna.

In accordance with an embodiment of the present invention, the circuitchip is an analog circuit chip for transmitting the signal to theantenna, and the electromagnetic wave transmitted from the circuit chipto the antenna is an electromagnetic wave caused by an operatingfrequency and harmonic components of the circuit chip.

In accordance with an embodiment of the present invention, mention, thecircuit chip is digital circuit chip, and the electromagnetic wavetransmitted from the circuit chip to the antenna is an electromagneticwave caused by an operating frequency and harmonic components of thecircuit chip.

In accordance with an embodiment of the present invention, one of thepair of transmission lines is formed in a first metal layer of theplurality of metal layers so as to transmit the signal to the antenna,and the electromagnetic bandgap structure includes a plurality of metalplates spaced apart from the one of the pair of transmission lines in adirection of the antenna, and a plurality of vias for connecting the oneof the pair of transmission lines and the metal plates to each other, inwhich sets of the metal plates and the vias are periodically arranged ata predetermined interval.

In accordance with an embodiment of the present invention, the other ofthe pair of transmission lines is formed in a second metal layer of theplurality of metal layers which is spaced apart from the first metallayer in a direction of the antenna, and the metal plates are formed inthe second metal layer.

In accordance with an embodiment of the present invention, the one ofthe pair of transmission lines is a ground plate, and the other of thepair of transmission lines is a feed line.

In accordance with an embodiment of the present invention, the other ofthe pair of transmission lines is formed in a second metal layer of theplurality of metal layers which is spaced apart from the first metallayer in a direction of the antenna, and the metal plates are formedbetween the first metal layer and the second metal layer.

In accordance with an embodiment of the present invention, the one ofthe pair of transmission lines is a ground plate, and the other of thepair of transmission lines is a feed line.

In accordance with an embodiment of the present invention, the other ofthe pair of transmission lines is formed around the one of the pair oftransmission lines on the first metal layer.

In accordance with an embodiment of the present invention, the one ofthe pair of transmission lines is a feed line, and the other of the pairof transmission lines is a ground plate.

In accordance with an embodiment of the present invention, the PCBfurther includes an organic titanium coating layer formed on an outersurface of each of the metal plates.

In accordance with an embodiment of the present invention, a pad forelectrically connecting the antenna and the transmission line to eachother is provided at a surface of the antenna, and the plurality ofmetal plates of the electromagnetic bandgap structure are periodicallyarranged so as to enclose the pad.

Various objects, advantages and features of the present invention willbecome apparent from the following description of embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS:

These and other features, aspects, and advantages of the presentinvention are better understood with regard to the following DetailedDescription, appended Claims, and accompanying Figures. It is to benoted, however, that the Figures illustrate only various embodiments ofthe present invention and are therefore not to be considered limiting ofthe invention's scope as it may include other effective embodiments aswell.

FIG. 1 is a cross-sectional view showing a PCB including anelectromagnetic bandgap structure, in accordance with an embodiment ofthe invention.

FIG. 2 is a perspective view showing the electromagnetic bandgapstructure of FIG. 1, in accordance with an embodiment of the invention.

FIG. 3 is a cross-sectional view showing a unit of the electromagneticbandgap structure of FIG. 1, in accordance with an embodiment of theinvention.

FIG. 4 is a cross-sectional view showing a unit array of theelectromagnetic bandgap structure of FIG. 1, in accordance with anembodiment of the invention.

FIG. 5 is a top plan view showing the unit array of the electromagneticbandgap structure of FIG. 1, in accordance with an embodiment of theinvention,

FIG. 6 is a perspective view showing an electromagnetic bandgapstructure, in accordance with an embodiment of the invention.

FIG. 7 is a cross-sectional view showing a unit of the electromagneticbandgap structure of FIG. 6, in accordance with an embodiment of theinvention,

FIG. 8 is a cross-sectional view showing a unit array of theelectromagnetic bandgap structure of FIG. 6, in accordance with anembodiment of the invention.

FIG. 9 is a top plan view showing the unit array of the electromagneticbandgap structure of FIG. 6, in accordance with an embodiment of theinvention.

FIG. 10 is a perspective view showing an electromagnetic bandgapstructure according to a further embodiment of the present invention, inaccordance with an embodiment of the invention.

FIG. 11 is a cross-sectional view showing a unit of the electromagneticbandgap structure of FIG. 10, in accordance with an embodiment of theinvention.

FIG. 12 is a cross-sectional view showing a unit array of theelectromagnetic bandgap structure of FIG. 10, in accordance with anembodiment of the invention.

FIG. 13 is a top plan view showing the unit array of the electromagneticbandgap structure of FIG. 10, in accordance with an embodiment of theinvention.

FIG. 14 is a 3-D perspective view showing an electromagnetic bandgapstructure, in accordance with an embodiment of the invention.

FIG. 15 is a sectional view showing the electromagnetic bandgapstructure of FIG. 14, in accordance with an embodiment of the invention.

FIG. 16 is a plan view showing, a configuration of the electromagneticbandgap structure of FIG. 14, in accordance with an embodiment of theinvention.

FIG. 17 shows an equivalent circuit of the electromagnetic bandgapstructure of FIG. 14, in accordance with an embodiment of the invention.

FIG. 18 is a 3-D perspective view showing an electromagnetic bandgapstructure, accordance with an embodiment of the invention.

FIG. 19 is a 3-D perspective view showing an electromagnetic bandgapstructure, in accordance with an embodiment of the invention,

FIG. 20 is a 3-D perspective view showing an electromagnetic bandgapstructure, in accordance with an embodiment of the invention.

DETAILED DESCRIPTION:

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, which illustrate embodiments ofthe present invention. This invention may, however, be embodied in manydifferent forms and should not be construed as limited to theillustrated embodiments set forth herein. Rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the present invention to those skilled in theart. Like numbers refer to like elements throughout. Prime notation, ifused indicates similar elements in alternative embodiments.

FIG. 1 is a cross-sectional view showing a PCB including anelectromagnetic bandgap structure, in accordance with an embodiment ofthe invention.

With reference to FIG. 1, a PCB 100 using an electromagnetic bandgapstructure 150 according to the embodiment of the present inventionincludes metal layers 110-1, 110-2, 110-3, 110-4, 110-5, 110-6(hereinafter, collectively referred to as “110”), dielectric layers120-1, 120-2, 120-3, 120-4, 120-5 (hereinafter, collectively referred toas “120”) disposed between the metal layers 110, a circuit chip 130mounted on the first upper metal layer 110-1, an antenna 140 mounted onthe first upper metal layer 110-1 and spaced apart from the circuit chip130, an electromagnetic bandgap structure 150 disposed between thecircuit chip 130 and the antenna 140 and between the first upper metallayer 110-1 and the second upper metal layer 110-2 (or between the firstupper metal layer 110-1 and the third upper metal layer 110-3), andsolder resists 160-1, 160-2 respectively formed in the first upper metallayer 110-1 and the lowermost metal layer 110-6.

Supposing that the metal layer 110-3 is a ground layer and the metallayer 110-4 is a power layer, current flows through a via 170 connectedbetween the ground layer 110-3 and the power layer 110-4, and the PCB100 performs a predetermined operation or function.

In accordance with at least one embodiment, the metal layer 110-1includes a pad 110 a for electrically connecting the antenna 140 and themetal layer to each other.

In accordance with at least one embodiment, the pad 110 a formed in themetal layer 110-1 is a feed pad or a ground pad. In the case where themetal layer 110-1 includes a feed line as a transmission line, the feedline contained in the metal layer 110-1 is connected to the antenna 140through a feed pad.

In the case where the metal layer 110-1 includes the feed line as above,the metal layer 110-2 or 110-3 includes a ground line (or a groundplate) as a transmission line. In this case, the ground line iselectrically connected to the antenna 140 through a via (not shown) andthe ground pad.

In addition, the metal layer 110-1 or the metal layer 110-2 or 110-3includes both the ground line and the feed line as transmission lines.

In accordance with at least one embodiment, when the antenna 140simultaneously uses the feed line and the ground line, which are a pairof transmission lines in the same PCB 100, an electromagnetic wave 180caused by an operating frequency and harmonic components of the circuitchip 130 is transmitted to between the ground line and the feed line ofthe antenna 140, undesirably causing a mixed signal problem.

The mixed signal problem means disturbing an accurate operation of theantenna 140 because the electromagnetic wave from the circuit chip 130has a frequency within the operating frequency band of the antenna 140.

For example, when the antenna 140 transmits or receives a predeterminedfrequency signal, the electromagnetic wave 180 including thepredetermined frequency signal is transmitted from the circuit chip 130,making it difficult to accurately transmit or receive the signal.

In order to solve such a mixed signal problem, in accordance withvarious embodiments of the present invention, the electromagneticbandgap structure 150 is mounted between the circuit chip 130 and theantenna 140 and also between the metal layer 110-1 having the feed lineand the metal layer 110-2 or 110-3 having the ground line, thus blockingthe transmission of the mixed signal to the antenna 140 from the circuitchip 130.

In accordance with at least one embodiment, the circuit chip 130 is anRE analog circuit chip directly connected to the antenna 140 through thefeed line or a digital circuit chip indirectly connected to the antenna40 through the RF analog circuit chip.

In the case of the digital circuit chip, it is not directly connected tothe antenna 140 as in the RF analog circuit chip, and thus may reduce aneffect of noise on the antenna 140.

However, the digital circuit chip deals with signals 0 and 1, and theinfluence of frequency is not negligible because the frequency fallswithin a high frequency band.

For this reason, in order to block noise between the antenna 140 and thedigital circuit chip, the bandgap structure may be mounted therebetween.

Specifically, in accordance with an embodiment, the bandgap structure isprovided between the antenna 140 and the analog circuit chip and/orbetween the antenna 140 and the digital circuit chip.

FIG. 2 is a perspective view showing the electromagnetic bandgapstructure of FIG. 1, FIG. 3 is a cross-sectional view showing a unit ofthe electromagnetic bandgap structure of FIG. 1, FIG. 4 is across-sectional view showing a unit array of the electromagnetic bandgapstructure of FIG. 1, and FIG. 5 is a top plan view showing the unitarray of the electromagnetic bandgap structure of FIG. 1, in accordancewith an embodiment of the invention.

With reference to FIGS. 2 to 5, the electromagnetic bandgap structureaccording to an embodiment of the present invention includes metalplates 150-1 formed in the first upper metal layer 110-1 and vias 150-2formed in the upper dielectric layer 120-1, and is formed on the groundplate (or ground line) 110-2 a, which is the transmission line formed inthe second upper metal layer 110-2.

In accordance with at least one embodiment, the ground plate 110-2 a isformed on the dielectric layer 120-2 and thus provides a ground for thetransmitted or received signal of the antenna 140.

The metal plates 150-1 are spaced apart from the upper surface of theground plate 110-2 a. The metal plates 150-1 are provided in the form ofa rectangular parallelepiped or a thin film, and are formed away fromthe ground plate 110-2 a.

In accordance with at least one embodiment, the metal plates 150-1 aredisposed to face the ground plate 110-2 a, thus making it possible toform capacitance between the metal plates 150-1 and the ground plate110-2 a.

In accordance with at least one embodiment, the metal plates 150-1 areformed of the same metal as that of the ground plate 110-2 a, thusenabling signal transmission.

The vias 150-2 connect the ground plate 110-2 a and the metal plates150-1 to each other. Specifically, the vias 150-2 extend perpendicularlyfrom the ground plate 110-2 a, so that one end of each via is connectedto the center of the metal plates 150-1.

In accordance with at least one embodiment, the vias 150-2 are formed ofthe same metal as that of the ground plate 110-2 a. In this case, thevias 150-2 enable the signal or structural connection between the groundplate 110-2 a and the metal plates 150-1.

In the electromagnetic bandgap structure, according to certainembodiments, the metal plates 150-1 and the vias 150-2 constituterespective units, and these units are periodically arranged atpredetermined intervals. As shown in the top plan view of FIG. 5, theunits are periodically arranged so as to enclose the feed pad 110 a′ andthe ground pad 110 a″ formed in the first upper metal layer 110-1, thusblocking the transmission of an electromagnetic wave from the circuitchip 130. Herein, a periodic array indicates that the units arerepeatedly arranged at predetermined intervals. Thus, the distancesbetween the units need not be uniform.

Furthermore, the dimension (e.g. interval, area or thickness) of theunits vary and are appropriately adjusted.

Although the formation of the electromagnetic bandgap structure betweenthe first upper metal layer 110-1 and the second upper metal layer 110-2is illustrated, the present invention is not limited thereto.Alternatively, the electromagnetic bandgap structure is formed betweenthe other metal layer and the dielectric layer.

FIG. 6 is a perspective view showing an electromagnetic bandgapstructure, FIG. 7 is a cross-sectional view showing a unit of theelectromagnetic bandgap structure of FIG. 6, FIG. 8 is a cross-sectionalview showing a unit array of the electromagnetic bandgap structure ofFIG. 6, and FIG. 9 is a top plan view showing the unit array of theelectromagnetic bandgap structure of FIG. 6, in accordance with anembodiment of the invention. In this embodiment, a feed line and aground line are present in the same plane.

With reference to FIGS. 6 to 9, the electromagnetic bandgap structureaccording to another embodiment of the present invention includes metalplates 150-1′ formed in a first upper metal layer 110-1 and vias 150-2′formed in an upper dielectric layer 120-1, and is formed on a feed line210 which is a transmission line. The feed line 210 is formed on adielectric layer 120-2 and transmits a signal. The signal passingthrough the feed line 210 becomes an electromagnetic wave having highfrequency.

In accordance with an embodiment of the invention, the metal plates150-1′ are spaced apart from the upper surface of the feed line 210. Themetal plates 150-1′ are provided in the form of a rectangularparallelepiped or a thin film, and are formed away from the feed line210 and the ground plate 110-2 a formed in the second upper metal layer110-2.

The metal plates 150-1′ are disposed so that partial surfaces thereofface the ground plate 110-2 a, thus making it possible to formcapacitance between the metal plates 150-1′ and the ground plate 110-2a.

In accordance with an embodiment of the invention, the metal plates150-1′ are formed of the same metal as that of the feed line 210, thusenabling signal transmission.

The vias 150-2′ connect the feed line 210 and the metal plates 150-1′ toeach other. Specifically, the vias 150-2′ extend perpendicularly fromthe feed line 210 so that one end of each via is connected to the centerof the metal plates 150-1′.

In accordance with an embodiment of the invention, the vias 150-2′ arealso formed of the same metal as that of the feed line 210. In thiscase, the vias 150-2′ enable the signal or structural connection betweenthe feed line 210 and the metal plates 150-1′.

In the electromagnetic bandgap structure, the metal plates 150-1′ andthe vias 150-2′ constitute respective units, and these units areperiodically arranged at predetermined intervals. As shown in the topplan view of FIG. 9, the units are periodically arranged so as toenclose the feed pad 110 a′ and the ground pad 110 a″ formed in thefirst upper metal layer 110-1, thus blocking, the transmission of anelectromagnetic wave from the circuit chip 130. Herein, a periodic arrayindicates that the units are repeatedly arranged at predeterminedintervals. Thus, the distances between the units need not be uniform.

Furthermore, the dimension (e.g., interval, area or thickness) of theunits vary, and are appropriately adjusted.

Although the formation of the electromagnetic bandgap structure betweenthe first upper metal layer 110-1 and the second upper metal layer 110-2is illustrated, the present invention is not limited thereto.Alternatively, the electromagnetic bandgap structure may be formedbetween the other metal layer and the dielectric layer.

FIG. 10 is a perspective view showing an electromagnetic bandgapstructure, FIG. 11 is a cross-sectional view showing a unit of theelectromagnetic bandgap structure of FIG. 10, 12 is a cross-sectionalview showing a unit array of the electromagnetic bandgap structure ofFIG. 10, and FIG. 13 is a top plan view showing the unit array of theelectromagnetic bandgap structure of FIG. 10, in accordance with anembodiment of the invention. In this embodiment, in the case where ametal layer 110-1 includes a feed line and a metal layer 110-3 includesa ground line (or a ground plate), the electromagnetic bandgap structureis disposed between the metal layers 110-1, 110-3.

With reference to FIGS. 10 to 13, the electromagnetic bandgap structureaccording to a further embodiment of the present invention includesmetal plates 150-1″ formed in a metal layer 110-2, organic titaniumcoating layers 311, 312, and vias 150-2″, and is formed on a groundPlate 110-3 a which is a transmission line formed in the metal layer110-3.

In accordance with an embodiment of the invention, the ground plate110-3 a and the metal plates 150-1″ are electrically connected to eachother using the vias 150-2″, and the metal plates 150-1″ and the vias150-2″ form respective mushroom type structures,

The first upper metal layer 110-1 includes a feed line 110-1 a, and thecircuit chip 130 transmits data to the antenna 140 through the feed line110-1 a.

In accordance with an embodiment of the invention, the mushroom typestructures consisting of the metal plates 150-1″ and the vias 150-2″ areformed between the ground plate 110-3 a and the feed line 110-1 a,giving a bandgap structure for blocking a signal included in apredetermined frequency band.

Dielectric layers 120-1, 120-2 are respectively interposed between themetal plates 150-1″ and the feed line 110-1 a and between the metalplates 150-1″ and the ground plate 110-3 a.

In accordance with an embodiment of the invention, the upper dielectriclayer 120-1 and the lower dielectric layer 120-2 are formed of the samedielectric material, or of dielectric materials having differentdielectric constants. For example, in order to further lower the bandgapfrequency, the upper dielectric layer 120-1 are formed of a dielectricmaterial having a higher dielectric constant than that of the dielectricmaterial of the lower dielectric layer 120-2.

In accordance with an embodiment of the invention, the thickness of eachof the lower dielectric layer 120-2 and the upper dielectric layer 120-1are appropriately adjusted, so as to obtain the bandgap frequencyapproximate to an intended bandgap frequency. Specifically, thethickness of the upper dielectric layer 120-1 are reduced and thethickness of the lower dielectric layer 120-2 are increased to thatextent, and thereby, even when using the electromagnetic bandgapstructure having the same size, the bandgap frequency is controlled tobe closer to an intended frequency band. The bandgap frequency means thefrequency of an electromagnetic wave that is suppressed from beingtransmitted from one side of the electromagnetic bandgap structure tothe other site thereof.

The mushroom type structures are repeatedly formed as shown in FIGS. 12and 13. Specifically, the metal plates are repeatedly disposed, and thevias are formed to equal in number the number of metal plates and areconnected thereto in respective units.

Although the metal plates are illustrated in the form of a square shapein FIGS. 10 to 13, they may have other shapes including polygonal suchas triangular or hexagonal, circular, or oval shapes.

When the mushroom type structures are repeatedly formed in this way, itis possible to block a signal having a frequency band corresponding toan operating frequency band of the circuit chip among an electromagneticwave proceeding from the circuit chip to the antenna.

In accordance with an embodiment of the invention, the organic titaniumcoating layers 311, 31.2 are disposed between the metal plates 150-1″and the dielectric layer 120-1 and between the ground plate 110-3 a andthe dielectric layer 120-2, in order to enhance the adhesivitytherebetween in a compression process. The organic titanium coatinglayers 311, 312 are formed on the surfaces of the metal plates 150-1″and the ground plate 110-3 a, and the dielectric layer 120-2 isinterposed between the metal plates 150-1″ and the ground plate 110-3after which compression is performed under conditions of hightemperature and high pressure, thereby forming a highly reliableelectromagnetic bandgap structure.

In the electromagnetic bandgap structure, the metal plates 150-1″ andthe vias 150-2″ constitute respective units, and these units areperiodically arranged at predetermined intervals. As shown in the top,plan view of FIG. 13, the units are periodically arranged, so as toenclose the feed pad 110 a′ and the ground pad 110 a″ formed in thefirst upper metal layer 110-1, thus blocking the transmission of theelectromagnetic wave from the circuit chip 130. Herein, a periodic arrayindicates that the units are repeatedly formed at predeterminedintervals. Thus, the distances between the units need not be uniform.

In accordance with an embodiment of the invention, the formation of theelectromagnetic bandgap structure between the first upper metal layer110-1 and the third upper metal layer 110-3 is illustrated, but thepresent invention is not limited thereto. Alternatively, theelectromagnetic bandgap structure may be formed between the other metallayer and the dielectric layer.

FIG. 14 is a 3-D perspective view showing an electromagnetic bandgapstructure, FIG. 15 is a sectional view showing the electromagneticbandgap structure of FIG. 14, and FIG. 16 is a plan view showing aconfiguration of the electromagnetic bandgap structure of FIG. 14, inaccordance with another embodiment of the present invention.Particularly. FIG. 15 show a section viewed along the AA line of FIG.14.

As shown in FIG. 14 through FIG. 16, the electromagnetic bandgapstructure in accordance with another embodiment of the present inventionincludes a plurality of metal plates 210 a, 210 b and 210 c, a metallayer 220 placed on a planar surface that is different from a planarsurface in which the metal plates 210 a, 210 b, and 210 c are placed anda stitching via 230 electrically connecting two adjacent metal platesamong the metal plates.

In other words, the electromagnetic bandgap structure 200 shown in FIG.14 through FIG. 16 includes a two-layered planar structure having aFirst layer in which the metal layer 220 is placed and a second layer inwhich the plurality of metal plates 210 a, 210 b and 210 c are placed. Adielectric layer is interposed between the metal layer 220 and theplurality of metal plates 210 a, 210 b and 210 c.

FIG. 14 through FIG. 16 show elements constituting the electromagneticbandgap structure (i.e., a part constituting the 2-layeredelectromagnetic bandgap including the stitching via) for the convenienceof illustration (also, in the case of FIG. 18 through FIG. 20).Accordingly, the first layer in which the metal layer 220 shown in FIG.14 through FIG. 16 is placed and the second layer in which the pluralityof metal plates 210 a, 210 b and 210 c shown in FIG. 14 through FIG. 16are placed is any two layers of a multi-layered printed circuit board.

In other words, it shall be obvious that there is at least oneadditional metal layer below the metal layer 220, above the metal plates210 a, 210 b and 210 c and/or between the metal layer 220 and the metalplates 210 a, 210 b and 210 c.

For example, the electromagnetic bandgap structure 200 shown in FIG. 14through FIG. 16 is placed between any two metal layers functioning as apower layer and a ground layer, respectively, in a multi-layered printedcircuit board, in order to block a conductive noise (the same can beapplied to electromagnetic bandgap structures shown in FIG. 18 to FIG.20 in accordance with an embodiment of the invention).

Since the conductive noise problem is not limited to the space betweenthe power layer and the ground layer, the electromagnetic bandgapstructure shown in FIG. 14 through FIG. 20 is placed between any twoground layers or power layers placed on different layers from each otherin a multi-layered printed circuit board.

In accordance with an embodiment of the present invention, metal plates210 a, 210 b and 210 c are spaced from each other at a predetermineddistance on the same planar surface. Here, the metal layer 220 and themetal plates 210 a, 210 b and 210 c are a material (e.g., copper (Cu))to which power is supplied and a signal is transmitted.

In accordance with an embodiment of the present invention, stitching via230 electrically connects two adjacent metal plates (e.g. the metalplates 210 b and 210 c in FIG. 14). However, the two metal plates 210 band 210 c are connected not on the same layer in which the metal plates210 b and 210 c are placed but through another layer (e.g. the metallayer 220) that is different from the layer in which the metal plates210 b and 210 c are placed.

The stitching via 230 is formed to include a first via 232, a connectionpattern 234 and a second via 236. The first via 232 includes one endpart, connected to the first metal plate 210 b, and the other end part,connected to one end part of the connection pattern 234. The second via236 includes one end part, connected to the second metal plate 210 c,and the other end part, connected to the other end part of theconnection pattern 234. A via land for being connected to the first via232 and/or the second via 236 is formed on either end part of theconnection pattern 234.

It shall be evident here that, in order to allow the metal plates to beelectrically connected to each other, it is necessary that a platinglayer be formed on an inner wall only of the first via 232 and thesecond via 236 of the stitching via 230 or the inside of the stitchingvia 230 be filled with a conductive material (e.g., conductive paste),and the connection pattern 234 be a conductive material, such as ametal.

In accordance with an embodiment of the present invention, the twoadjacent metal plates 210 b and 210e are connected in series through thestitching via 230. In particular, the two adjacent metal plates 210 band 210 c are electrically connected in series in the order of the firstmetal plate 210 b→the stitching via 230 (the first via 232→theconnection pattern 234→the second via 236)→the second metal plate 210 b.

The first metal plate 210 b is connected to the other metal plate 210 athrough the stitching via 230. The second metal plate 210 c is alsoconnected to another metal plate (not shown) through the stitching via230. As a result, all metal plates, placed on the second layer, areconnected in series through the stitching via 230.

In accordance with an embodiment of the present invention, the metallayer 220 is formed with a clearance hole 225 accommodating theconnection pattern 234. The clearance hole 225 also accommodates the vialand for easy connection with the first via. 232 and/or the second via236 as well as the connection pattern 234. The clearance hole 225 allowsthe stitching via 230 and the metal layer 220 to be electricallydisconnected from each other.

Connecting the metal plates 210 a, 210 b and 210 c through the stitchingvia 230 makes it unnecessary to form a pattern for connecting the metalplates 210 a, 210 b and 210 c on the second layer. This makes the metalplates 210 a, 210 b and 210 c smaller and the gap between the metalplates 210 a, 210 b and 210 c narrower, increasing the capacitance inthe gaps between the metal plates 210 a, 210 b and 210 c.

FIG. 17 shows an equivalent circuit of an electromagnetic bandgapstructure having the above structure, in accordance with an embodimentof the invention.

Comparing the equivalent circuit of FIG. 15 with the electromagneticbandgap structure of FIG. 14, an inductance component L1 corresponds tothe fist. via 232, and an inductance component L2 corresponds to thesecond via 236. An inductance component L3 corresponds to the connectionpattern 234. C1 is a capacitance component by the metal plates 210 a and210 b and another dielectric layer and another metal layer to be placedabove the metal plates 210 a and 210 b. C2 and C3 are capacitancecomponents by the metal layer 220 placed on the same planar surface asthat of the connection pattern 234 and another dielectric layer andanother metal layer are placed below the planar surface of theconnection pattern 234.

The electromagnetic bandgap structure shown in FIG. 14 through FIG. 16functions as a band stop filter, which blocks a signal of a certainfrequency band according to the above equivalent circuit. In otherwords, as seen in the equivalent circuit of FIG. 15, a signal x of a lowfrequency band (refer to FIG. 17) and a signal y of a high frequencyband (refer to FIG. 17) pass through the electromagnetic bandgapstructure, and signals z1, z2 and z3 of a certain frequency band (referto FIG. 17) ranging between the low frequency band and the highfrequency band are blocked by the electromagnetic bandgap structure.

In accordance with an embodiment of the present invention, the metalplates 210 a, 210 b and 210 c are placed on a planar surface in whichanother metal layer that is different from the metal layer 220 isplaced. The metal plate 210 a placed at a far left side, therefore, areconnected to the other metal layer that is different from the metallayer 220 through a stitching via., in accordance with the presentinvention.

If the metal layer 220 is a power layer, the different metal layer is aground layer, and if the metal layer 220 is a ground layer, thedifferent metal layer is a power layer.

Alternatively, a signal is transferred in a predetermined direction byallowing the metal layer 220 to be the ground layer and the other metallayer to be a signal layer, and the noise of a certain frequency of thesignal is reduced by allowing the mentioned metal plates 210 a, 210 band 210 c and the stitching via 230 to be arranged on some areas of asignal transfer path of the signal layer.

As shown in FIG. 14 through FIG. 16, the metal plates 210 a, 210 b and210 c are arranged in one row, and two stitching vias are connected toeach of the metal plates 210 a, 210 b and 210 c. However, in accordancewith another embodiment of the present invention, a metal plate isarranged in a matrix of m*n, m and n being natural numbers, and itsadjacent metal plates are connected by using the stitching via. In thiscase, each metal plate functions as a path connecting its adjacent othermetal plates and be connected to at least two stitching vias.

In other words, the connection form shown in FIG. 14 through FIG. 16 ismerely an example, and as long as all metal plates form a closed loop bybeing electrically connected to each other, any method of connecting themetal plates through the stitching via is used.

Hereinafter, some electromagnetic bandgap structures in accordance withanother embodiments of the present invention will be described in turnwith reference to FIG. 18 through FIG. 20. Any matter already describedin FIG. 14 through FIG. 16 will be not be redundantly described, and theelectromagnetic bandgap structures will be briefly described based onthe features of each embodiment of the present invention. This isbecause the same technological principle as described in FIG. 14 throughFIG. 16 is applied to the electromagnetic bandgap structures of FIG. 18through FIG. 20 in accordance with another embodiments of the presentinvention, except for some differences.

Accordingly, in FIG. 18 through FIG. 20, each corresponding element isassigned the identical reference numeral as in FIG. 14 through FIG. 16,for easy comparison.

As shown in FIG. 18, the electromagnetic bandgap structure in accordancewith another embodiment of the present invention includes a plurality ofmetal plates 210 a, 210 b and 210 c and a stitching via 230 electricallyconnecting two adjacent metal plates of the metal plates 210 a, 210 band 210 c to each other. In other words, the electromagnetic bandgapstructure of FIG. 18 does not have a metal layer corresponding to themetal layer 220 shown in FIG. 14 through FIG. 15.

As such, it is not always necessary that the electromagnetic bandgapstructure having a stitching via in accordance with another embodimentof the present invention include a metal layer below an area in whichthe stitching via and metal plates are placed. This is because it is notnecessary that the connection pattern 234 of the stitching via 230 beformed on an area in which the metal layer is placed.

In other words, if there is a metal layer on the same planar surface tocorrespond to an area in which the connection pattern 234 will beplaced, the connection pattern 234 is manufactured in the form of beingaccommodated into the clearance hole 225 formed in the metal layer 220on the same planar surface, as shown in FIG. 14 through FIG. 16.However, no additional metal layer is placed in the area in which theconnection pattern 234 will be placed, as shown in FIG. 18. Of course,there may be a dielectric layer below the metal plates in FIG. 1.8.

As shown in FIG. 19, the electromagnetic bandgap structure in accordancewith another embodiment of the present invention has a stackedstructure,the position of the upper layer and the lower layer inversedfrom that of FIG. 14 through FIG. 16.

In other words, while the electromagnetic bandgap structure shown inFIG. 14 through FIG. 16 has the metal layer 220 forming a lower layer,the metal plates 210 a, 210 b and 210 c forming an upper layer and thedielectric layer interposed between the lower layer and the upper layer,the electromagnetic bandgap structure shown in FIG. 19 inversely havethe metal layer 220 forming the upper layer, the metal plates 210 a, 210b and 210 c forming the lower layer and the dielectric layer interposedbetween the lower layer and the upper layer. Of course, it can beexpected that the electromagnetic bandgap structure shown in FIG. 19 hasthe identical or similar noise blocking effect to that of FIG. 14through FIG. 16.

As shown in FIG. 20, the electromagnetic bandgap structure in accordancewith another embodiment of the present invention has the same structureof the electromagnetic bandgap structure shown in FIG. 19 without themetal layer 220. This reason, already described above with reference toFIG. 18, will be omitted.

The electromagnetic bandgap structure in accordance with the presentinvention can have various types of stacked structures. Although all ofthe foresaid drawings show that all metal plates are stacked in the sameplanar surface, it is not always necessary that all metal plates arestacked in the same planar surface.

In case at least one of the metal plates is stacked in a planar surfacethat is different from the planar surface in which the other metalplates are stacked, the electromagnetic bandgap structure will have twoor more layers. However, this increased number of layers may have nodisadvantageous effect on the design when the electromagnetic bandgapstructure of the present invention is applied to a multi-layered printedcircuit board.

The aforementioned drawings also show that each stitching viaelectrically connects two adjacent metal plates to each other. However,it may be unnecessary that two plates connected by the stitching via areadjacent to each other.

Even though one metal plate is shown to be connected to another metalplate through one stitching via, it is obviously unnecessary that theelectromagnetic bandgap structure has any limitation to the number ofthe stitching vias connecting any two metal plates.

For the convenience of illustration and understanding of the invention,in FIG. 14 through FIG. 20, only three metal plates are shown, and onemetal plate is electrically connected to another adjacent metal plateand yet another adjacent metal plate through /one stitching via each(i.e. two adjacent cells around one cell are connected).

In addition, the organic titanium coating layer formed on outer surfacesof the metal plates may be further included.

As described hereinbefore, embodiments of the present invention providea PCB including an electromagnetic bandgap structure. According toembodiments of the present invention, the electromagnetic bandgapstructure is disposed between the circuit chip and the antenna, thusefficiently reducing unnecessary signal interference,

Also, according to embodiments of the present invention, there is noneed for additional change in antenna design in order to block noise,thus shortening the lead time.

Also, according to embodiments of the present invention, as the leadtime is shortened, additional costs do not occur.

Embodiments of the present invention may suitably comprise, consist orconsist essentially of the elements disclosed and may be practiced inthe absence of an element not disclosed. For example, it can berecognized by those skilled in the art that certain steps can becombined into a single step.

The terms and words used in the present specification and claims shouldnot be interpreted as being limited to typical meanings or dictionarydefinitions, but should be interpreted as having meanings and conceptsrelevant to the technical scope of the present invention based on therole according to which an inventor can appropriately define the conceptof the term to describe the best method he or she knows for carrying outthe invention.

As used herein, terms such as “first,” “second,” “one side,” “the otherside” and the like are arbitrarily assigned and are merely intended todifferentiate between two or more components of an apparatus. It is tobe understood that the words “first,” “second,” “one side,” and “theother side” serve no other purpose and are not part of the name ordescription of the component, nor do they necessarily define a relativelocation or position of the component. Furthermore, it is to beunderstood that the mere use of the term “first” and “second” does notrequire that there be any “third” component., although that possibilityis contemplated under the scope of the embodiments of the presentinvention.

The singular forms “a,” “an,” and “the” include plural referents, unlessthe context clearly dictates otherwise.

As used herein and in the appended claims, the words “comprise,” “has,”and “include” and all grammatical variations thereof are each intendedto have an open, non-limiting meaning that does not exclude additionalelements or steps.

Ranges may be expressed herein as from about one particular value,and/or to about another particular value. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value and/or to the other particular value, along withall combinations within said range.

Although the present invention has been described in detail, it shouldbe understood that various changes, substitutions, and alterations canbe made hereupon without departing from the principle and scope of thepresent invention. Accordingly, the scope of the present inventionshould be determined by the following claims and their appropriate legalequivalents.

What is claimed is:
 1. A printed circuit board, comprising: an antenna;a circuit chip; a plurality of metal layers and a plurality ofdielectric layers; a pair of transmission lines configured to transmit asignal to the antenna; and an electromagnetic bandgap structure disposedbetween the antenna and the circuit chip in the printed circuit boardand configured to prevent an electromagnetic wave from being transmittedfrom the circuit chip to the antenna, wherein the electromagneticbandgap structure comprises a dielectric layer; a plurality ofconductive plates; and a stitching via configured to electricallyconnect the conductive plates to each other, and wherein the stitchingvia passes through the dielectric layer, and a part of the stitching viais placed in a planar surface that is different from a planar surface inwhich the conductive plates are placed.
 2. The printed circuit board asset forth in claim 1, wherein the stitching via comprises: a first viapassing through the dielectric layer and having an end part beingconnected to any one of two adjacent conductive plates, and a second viapassing through the dielectric layer and having an end part beingconnected to the other of two adjacent conductive plates; and aconnection pattern having one end part being connected to the other endpart of the first via and the other end part being connected to theother end part of the second via.
 2. The printed circuit board as setforth in claim 2, further comprising: a conductive layer, wherein thedielectric layer is placed between the conductive plates and theconductive layer.
 4. The printed circuit board as set forth in claim 3,wherein the conductive layer comprises a-clearance hole, and theconnection pattern is accommodated in the clearance hole.
 5. The printedcircuit board as set forth in claim 1, wherein the conductive plateshave a polygonal, circular or elliptical shape.
 6. The printed circuitboard as set forth in claim 1, wherein the conductive plates have thesame size
 7. The printed circuit board as set forth in claim 1, whereinthe conductive plates are distinguished into a plurality of groupshaving different conductive plate sizes.
 8. The printed circuit board asset forth in claim 1, wherein the conductive plates are placed on thesame planar surface.